3974 OGATAAND AOKI
The Journal of Organic Chemistry
Anal. Calcd for CllHla (2,5-dihydro-5-phenyl-cis-2-pentene): C, 89.19; H, 10.81. Found: C, 89.39; H, 10.79. Reduction of 2,5-Dihydroallylbenzene. Undivided Cell, Ethanol Present.-Lithium chloride (5 g, 0.12 mol), absolute ethanol (4 g, 0.09 mol), and 2 g of material (87% 2,5-dihydroallylbenzene and 13’% 2,5-dihydro-n-propylbenzene)*’were placed in a 100. cc three-neck flask along with 60 cc of methylamine. A current of 0.5 A was passed through the system for 1 hr and 46 min (3180 C). The product, 1.8 g (go%), was shown by glpc (4-ft, LAC 446 column, 60’) to consist of 2,5-dihydroallylbenzene (34%) and 2,5-dihydro-n-propylbenzene(66%) as adjudged by their respective retention times. Anal. Calcd for C9H12 (2,5-dihydroallylbenzene): C, 89.94; H, 10.06. Found: C, 89.96; H, 10.09. Reduction of 2,S-Dihydro4-phenyl-l-butene.Undivided Cell, Ethanol Present.-Lithium chloride (5 g, 0.12 mol), absolute ethanol (4 g, 0.09 mol), and 1.5 gof material (90% 2,5-dihydro-4phenyl-1-butene, 5% 2,5-dihydro-n-buty1benzeneland 5% 4phenyl-l-butene)28were electrolyzed in a 100-cc three-neck flask by passing a current (0.5 A) for 76 min (2280 C). There was obtained 1.2 g (80%:) of material consisting of 2,5-dihydro-nbutylbenzene (31%) and 2,5-dihydro-4-phenyl-l-butene (69%). These compounds were identified by matching their retention (27) This material was obtained by preparative glpc (a combination of a 15-ft. 24% Zonyl E-7 column and a 15-ft 24% Carbowax 20 M column was used) from the products of the reactions described in Table V. (28) A mixture obtained by preparative glpc (same columns and conditions as described in ref 27) from the products of the reactions summarized in Table VI.
times (glpc) with the products obtained from the reductions of 4-phenyl-1-butene (Table VI ) Reduction of 2,S-Dihydro-5-phenyl-I-pentene.Undivided Cell, Ethanol Present.-In a manner completely analogous to that described above for the dihydro-1-butene, 1.3 g of materiale9 [2,5-dihydro-5-phenyl-l-pentene (95%) and 5-phenyl-1-pentene (5%)] was electrolyzed by passing a current (0.5 A) for 59 min (1770 C). The product (1.2 g, 91%) consisted of (analysis by glpc, 20-ft, 25% Carbowax 1540 column, 150’) 5-phenyl-lpentene (3%), 2,5-dihydro-5-phenyl-l-pentene,(76%), and 2,5dihydro-n-pentylbenzene (21%). Anal. Calcd for CllHla (2,5-dihydro-5-phenyl-l-pentene): C, 89.19; H, 10.81. Found: C, 89.15; H, 10.95.
.
Registry No.-(2,5-Dihydrod-phenyl)-cis-2-pentenel 21593-20-9; 2,5-dihydroallylbenzene, 21902-31-8; (2,5dihydro-5-phenyl)-l-pentene, 21902-32-9; 1-octene, 111-66-0; cis-2-octene, 7642-04-8 ; cis-4-octene, 764215-1; allylbenzene, 300-57-2; 4-phenyl-l-butene, 76856-9. Acknowledgment.-This research was sponsored by the Air Force Office of Scientific Research, Office of Aerospace Research, U. S. Air Force under AFOSR Grant 822-67. (29) Obtained by preparative glpc (same columns and conditions as described in ref 27) from the products of reduction of 5-phenyl-1-pentene.
Reaction of Alkyl Iodides with Peracetic Acid in the Presence of Aromatic Compounds’ YOSHIROOGATAAND KEIZOAOKI Department of Applied Chemistry, Faculty of Engineering, Nagoya University, Chikusa-ku, Nagoya, Japan Received March 6, 1969 Treatment of n-alkyl iodides with peracetic acid in the presence of aromatic compounds in acetic acid a t 30’ affords alkyl acetates and often iodo aromatic compounds in good yields. The rate of the reaction for a mixture of methyl iodide, peracetic acid, and m-xylene can be expressed as v = k [ C H J ][CHaCOaH] and is independent of the concentration of m-xylene. The structure of alkyl iodides affects the yield of iodoaromatic compound in the decreasing order n-alkyl > sec-alkyl > t-alkyl. The reaction mechanism is briefly discussed in terms of the effect of structure on the kinetics and product composition.
Among the reactions of alkyl iodides, the substitution of iodide by nucleophilic reagents such as hydroxide, phenoxide, alkoxide, and halide ions and other solvent molecules has been studied extensively.2 The kinetic studies on oxidation with peracids which have electrophilic oxygen have been reported, e.g., epoxidation of olefins and oxidat,ion of aldehydes, ketones, amines, aromatic hydrocarbons, and sulfur corn pound^.^-^ Also, oxidation of iodide ion by peracids or by peroxides has been used as a standard method for the quantitative analysis of peroxides or per acid^.^^^ During our kinetic study of iodoacetoxylation of olefins, it was observed (1) Contribution No. 132. (2) (a) J. Hine. “Physical Organic Chemistry,” 2nd ed, McCraw-Hill Book Co., Inc., New York, N. Y., 1962, Chapters 6 and 7, pp 157-185; (b) E. S. Gould, “Mechanism and Structure in Organic Chemistry.” Henry Holt and Co., New York, N. Y., 1959, Chapter 8, pp 250-305; (e) C. K. Ingold, “Structure and Mechanism in Organic Chemistry,” Cornel1 University Press, Ithaca, N. Y., 1953, Chapter 7, pp 306-418; (d) D. Segaller, J . Chem. Soc., 108, 1154 (1913); (e) E. L. Eliel, “Steric Effects in Organic Chemistry,” M. 5. Newman, Ed., John Wiley & Sons, Inc., New York. N. Y., 1956, Chapter 2, pp 61-163; (f) C. A. Bunton. “Nucleophilic Substitution a t a Saturated Carbon Atom,” Elsevier Publishing Co., New York, N. Y., 1963; (g) A. Streitwieser, Chem. Rev., 66, 571 (1956). (3) D. Swern, ibid.. 46, 1 (1949). (4) J. B. Lee and B. C. Uff, Quart. Rev. (London), 429 (1967). (5) A. G. Davies, “Organic Peroxides.” Butterworth and Co. Ltd., London, 1961, p 138. (6) J. 0. Edwards, “Inorganic Reaction Mechanisms,” W. A. Benjamin Inc., New York, N. Y.. 1964, Chapter 5.
that alkyl iodides liberate iodine on treatment with peracetic acid.7 However, few reports have thus far appeared on the oxidation of alkyl iodides with peracids.* There are several methods for iodination of aromatic compounds with molecular iodine, and these reactions usually require oxidizing agents such as nitric acid, periodic acid, sulfur trioxide, peroxides, or silver sulfate.gc10 We have previously suggested an aromatic iodination with a mixture of iodine and peracetic acid and postulated a mechanism explaining its autocatalytic n a t ~ r e . ~ We have found that molecular iodine in the above reaction can be replaced by alkyl iodide in some cases, and we wish to report in the present paper a novel aromatic iodination with a mixture of alkyl iodides and peracetic acid in acetic acid, which is exemplified by (7) Y. Ogata and K. Aoki. J . 01.8. Chem.. S i , 1625 (1966). (8) (a) L. F. Fieser and M. Fieser, “Advanced Organic Chemistry,’’ Reinhold Publishing Corp., New York, N. Y., 1961, p 789; (b) J. B. Dence and J. D. Roberts, J . Orp. Chem., 88, 1251 (1968); (c) D . F. Banks, Chem. Rev., 66,243 (1966). (9) Y. Ogata and K. Aoki, J. Amer. Chem. Soc., 90, 6187 (1968). (10) (a) J. K. Kochi, B. M. Graybill. and M. Kura, ibid., 86, 5257 (1964); (b) L. S. Silvert, D. Swern, and T. Asahara, J. Or@. Chem., 88, 3670 (1968); (c) P. B. D. de la Mare and J. H. Ridd, “Aromatic Substitution, Nitration and Halogenation,” Butterworth and Co. Ltd., London, 1959.
REACTION OF ALKYLIODIDES WITH PERACETIC ACID 3975
Vol. 34, No.12,December 1969
TABLE I REACTION OF ALKYLIODIDES (RI) AND PERACETIC ACIDIN THE PRESENCE OF XYLENE (ArH) IN ACETICACID AT 30" Alkyl group, R
X 101 MCHaCOiH
-Reactants,
RI
Reaction time, days
ArH
RI'
Products, X 101 Ma,* CHaCOaR (%) Arid (%I
180' Some Some 2.64 (73) 3.60 8.17 Methyl 9.89 2 Some Some 1 . 5 1(74) 2.03 8.06 Ethyl 5.04 10 2.55 1.66 (70) 1.59 (66) 2.39 8.08 n-Propyl 4.92 0.80 2.79 (123) 0.02 (0.8) 2.27 8.07 9 Isopropyl 4.92 1.81 (79) 2.57 1.78 (78) 2.29 8.06 9 n-Butyl 4.93 1.13 1.00 (71) 14 Small 1.41 8.12 Isobutyl 2.54 0.01 (0.6) 0.82 0.61 (45) 8.10 6 1.36 sec-Butyl 2.57 0.93 (69) 0.00 (0) Small 1.36 8.12 t-Butyl 2.43 6 1.20 1.06 (72) 1.13 (77) 16 1.47 8.08 n-Amyl 2.56 1 . 1 3(55) 0.57 (28) 2.92 2 2.04 8.05 Isoamyl 4.99 1 . 0 6(73) 1.08 (74) 1.31 16 8.11 1.46 n-Hexyl 2.53 2 1.55 (76) 1.01 (51) 2.32 8.05 2.03 n-Octyl 4.64 0.00 (0) Small Some 3 8.05 2.03 Cvclohexvl 4.89 Benzyl 2.44 1.40 8.09 12 Small 1.98(141) 0.19 (13)' Yields are based on peracetic acid used. b Some or small means that quantitative analysis has not been done. Iodo-m-xylene. Minutes. f Bibenzyl was not detected in the products.
12
(%)
0.02 (1) 0.03 (3) 0.04 (4) 1.69(149 0.01 (1) 0.02 (3) 0.30 (44) 0.93 (137 0.02 (3) 0.47 (46) 0 . 0 3 (4) 0.15 (20) 0.21 (20) 1.00 (143) Recovered.
the reaction of n-butyl iodide with a mixture of peracetic acid and m-xylene (eq 1). 2.00 p
CdHJ
+
3
+
CH3C03H
CHICOIH,
CH3
r'
N
+
Y
CH,COOC,&
+
HZO
(1)
1.50
r-l 0) N Q
CH,
Q
I
s5r
Results and Discussion
.E
5 Q
The reaction of a mixture of alkyl iodide, peracetic acid, and an aromatic compound was carried out in acetic acid a t 30". The results are shown in Table I. The table shows that the stoichiometry of the reaction can be expressed as in eq 2. Isobutyl iodide gives a RI
+ CHICOIH + ArH
-
1.00
UI
0 . c I
U 0
az 0.5C
in CHaCOzH
+
+
ArI CHICOOR HzO (2) methyl, ethyl, n-propyl, n-butyl, n-amyl, and n-hexyl; ArH = m-xylene or mesitylene
R
=
high yield of aromatic iodide but a low yield of isobutyl acetate. Isoamyl iodide affords a lower yield of iodo aromatics than other primary iodides. Secondary alkyl iodides such as isopropyl and secbutyl iodides give very poor yields of aromatic iodide, where a large amount of molecular iodine is liberated. No iodo-m-xylene was obtained with cyclohexyl iodide. With benzyl iodide, benzyl acetate and iodine are the main products and a low yield of iodo-m-xylene is obtained. No bibenzyl, i.e., a coupling product of benzyl radical, is detected by glpc. I n the reaction of t-butyl iodide, t-butyl acetate and iodine, but no iodo-m-xylene, were obtained. The reaction of alkyl iodide with peracetic acid without aromatic compound under the same conditions affords high yields of iodine and alkyl acetates as confirmed by glpc analysis. Kinetic study was conducted in acetic acid a t 30" by estimating the rate of formation of iodo aromatic
0
30
60
90
120
150
Tirne,rnin.
Figure 1.-Reaction of methyl iodide, peracetic acid, and mxylene in acetic acid a t 30'. Conversion curves of formation of iodo-m-xylene. Initial concentrations are the same as those in Table 11.
compound and the rate of consumption of peracetic acid. As seen in Figures 1 and 2, Tables I1 and 111, the rate of the reaction of methyl iodide-peracetic acid-m-xylene a t an early stage can be expressed as u = IC [CHJ] [CHaC03H], and it is independent of the concentration of m-xylene. The value of the calculated rate constant decreased with the progress of the reaction, probably because of the liberation of iodine, which is less reactive than alkyl iodide. The rate is firstorder both in methyl iodide and peracetic acid. The average rate constant k for the formation of iodo-mxylene is 2.09 X M-' sec-' and it is nearly equal
3976
The Journal of Organic Chemistry
OGATA AND f l O K I
TABLE I1 SECOND-ORDER RATECONSTANTS OF THE REACTION OF METHYL IODIDE-PERACETIC ACID-TWXYLENE IN ACETICACID AT 30" AND THE YIELDOF IODO AROMATIC COMPOUND Concentration X 102--M Time, Concentration X 101 M , Curve in kb I
CH~I
CHrCOaH
m-Xylene
min
A d (%)"
9.95 10.00 9.89 9.94 4.98 2.54 9.93 9.96 10.01 10.04
7.20 3.50 3.60 1.80 3.60 3.60 3.60 3.60 3.60 2.00"
8.15 10.03 8.17 8.24 8.23 8.18 4.11 2.11 10. 14c 10.09
300 1500 180 500 490 2330 350 2320 484 366
4.51 (63) 2.08(60) 2.64 (73) 1.04 (58) 2.11 (59) 2.12 (84) 1.90(53) 1 . 9 5 (93) 2.45 (68)d 0.01 (0.6)
Figure 1
X 10: M - 1 sec-1
A
2.23 2.35 2.15 1.84 2.14 2.21 2.01 1.85 1.97
... B D C
E B' B"
Av2.09 The yield of iodo-m-xylene is based on the reactant of the smallest amount. Rate constant k was calculated from iodo-m-xylene formation by v = k[CHJ] [CHsCOsH] a t an early stage of the reaction. Mesitylene. Iodomesitylene. The yield was 79% after 16 days. e Phenyl iodine diacetate. 2.90
TABLE I11 SECOND-ORDER RATECONSTANTS OF THE REACTION OF METHYL IODIDE-PERACETIC ACID-m-XYLENE I N ACETIC ACIDAT 30' Concentration X 101 MCHaCOsH m-Xylene
I-
2.50
CHaI
Curve in Figure 2
x
ka 10'
M -1 see-1
2.28 2.27 2.09 2.12 2.38 G 2.24 F 2.35 J 2.07 I 2.22 H 2.10 Av 2.21 a Rate constant k was calculated from peracetic acid consumption by v = k[CHaI] [CH8C03H]at an early stage of the reaction. 10.27 10.27 10.20 10.33 5.11 5.14 2.52 10.19 10.24 10.43
i 9
N
-
2.00
n
H"
U
+
n
I "
8 p
-
1.50
0
U
1.00
0.70
0
30
60
90 Time, min.
120
150
Figure 2.-Reaction of methyl iodide, peracetic acid, and mxylene in acetic acid at 30". Conversion curves of consumption of peracetic acid. Initial concentrations are the same as those in Table 111.
to that for the consumption of peracetic acid (2.21 X M-l sec-l). The rate of formation of iodomesitylene is the same as that of iodo-m-xylene, showing that the rate-determining step is the bimolecular reaction of alkyl iodide and peracetic acid. The effect of alkyl group of alkyl iodide on the rate constant k X lo3 M-' sec-l for iodination of m-xylene calculated from peracetic acid consumption is as follows: CH3, 2.2; CzHs, 4.0; n-C4H9, 5.0. This observed reactivity of alkyl iodides toward peracetic acid, CHJ < CzHJ < n-C4HJ, is reverse to that of the ordinary S ~ 2 - t y p ereaction,2 and it suggests that the ~ in present reaction is of electrophilic or of S E type nature.
5.80 5.83 2.93 2.90 5.76 2.84 2.85 2.79 2.85 2.81
8.10 8.10 8.09 8.12 8.11 8.14 8.14 16.21 4.02 1.96
The reaction of n-alkyl iodide is generally accompanied by the liberation of a small amount of iodine; this occurs to a remarkable extent with n-propyl, n-hexyl, and n-octyl iodides, but only to a small extent with ethyl iodide and especially with n-butyl, n-amyl, and methyl iodides. The amount of formed iodine increases a t early stages of the reaction when molar ratios [CHJ]/ [CH3C03H]and [CH31]/ [m-xylene] increase in the reaction of methyl iodide-peracetic acidm-xylene, in view of the coloration of iodine and also curves H, I, and J in Figure 2. The yields of iodine and iodo-m-xylene change with the structure of alkyl iodides, as shown in Table I. These facts indicate the competition between aromatic iodination and liberation of iodine (eq 5 and 6). It was confirmed that n-alkyl and sec-alkyl iodides are stable toward solvolysis in an acetic acid solution under these conditions. We have reported that an iodo aromatic compound is oxidized by peracetic acid to aryl iodine diacetate, which is a more active oxidant than peracetic acid in the aromatic iodination with iodine. When peracetic acid was replaced by phenyl iodine diacetate in acetic acid a t 30" in a reaction with methyl iodide-m-xylene, the yield of iodo-m-xylene became very low, as shown in the last line of Table 11. This result suggests that alkyl iodide is very slowly oxidized by aryl iodine diacetate, which is an effective oxidizing agent for the accelera-
Vol. 34, No. 1.2, December 1969
REACTION OF ALKYLIODIDES WITH PERACETIC ACID 3977
tion of aromatic iodi~iation.~Therefore, no autocatalysis is observed in the present reaction and the possible formation of aryl iodine diacetate may have an effect to lower the yield of iodo-m-xylene in the present reaction. Unlike aryl iodide, alkyl iodide cannot afford stable alkyl iodine diacetate.* Hence, the reaction of alkyl iodides with peracetic acid in acetic acid in the absence of aromatic compound affords molecular iodine and alkyl acetates in good yield, whereas in the presence of an aromatic compound, iodination of the aromatic compound occurs. The mechanism of the aromatic iodination a t initial stages of the reaction may be expressed as shown in eq 3-5, which fit the fact that the rate is independent slow
+ CHBOOR HOI + CHaCOzH e CHICOZT+ Hz0 ArH + CH3COzI% ArI + CHICOZH R I $- CH3C03H ---f HOI fast
(3) (4 1
(5)
of the concentration of the aromatic compound, ArH. Liberation of iodine may arise from reaction 6. RI
+ CHaCOzI
fast
CH3COzR
+ Iz
(6)
From the kinetic results it can be seen that aromatic iodination does not take place with molecular iodine via eq 6 and 7, but through active iodinating agents Ip
+ CH8CO3H + 2ArH +2ArI + H 2 0 + CHaCOZH (7)
such as CH3C021or HOI which is formed by the bimolecular reaction of alkyl iodide with peracetic acid. Thus, the rate of the reaction of iodine with peracetic acid in acetic acid is expressed as v = k [I21 [CH3C03H], where k is ca. 2 X M-l sec-' at 30°,? which is a much lower rate than that for the reaction of alkyl iodide and peracetic acid in the presence and absence of aromatic compounds. Equation 3 might proceed either by direct electrophilic bimolecular substitution reaction or via an unstable aliphatic; iodoso compound or iodoso diacetate. I n the case of n-alkyl iodides, the reaction proceeds mainly by eq 3, 4, and 5, while in the case of s e e and t-alkyl iodides the reaction may go by way of eq 3, 4 and 6. Equation 6 is preferred to eq 5 in secondary and tertiary alkyl iodides, probably because the abstraction of iodide ion from R I by iodonium ion derived from CH3COOIis easier than from the corresponding primary iodide. Experimental Section Materials.-Commercial methyl and ethyl iodides of reagent grade were used without further purification. Other alkyl iodides were prepared by refluxing respective alcohols with a mixture of iodine and red phosphorus.ll Benzyl iodide was prepared by refluxing benzyl chloride and potassium iodide in ethanol.lZ Boiling points of the prepared iodides are indicated as follows: n-propyl, bp 101.7-102.3'; isopropyl, bp88.7-89.0"; n-butyl, bp 130-131 '; isobutyl, bp 119-120.5'; sec-butyl, bp 119.0-120.0'; t-butyl, bp 28' (47 mm); n-amyl, bp 77.0-77.2' (65 mm); isoamyl, bp 145-147'; n-hexyl, bp 83-85' (36 mm); (11) R. Adams and V. Voorhees, J . Amer. Chem. SOC.,41, 789 (1919). (12) G . H. Coleman and C. R. Hauser, ibid., 60, 1193 (1928).
n-octyl, bp 65.5-72.0' (2 mm); cyclohexyl, bp 59.0-59.8' (7 mm); benzyl, bp 79-80' (5 mm). Commercial methyl, ethyl, and n-butyl acetates of reagent grade were used for the authentic samples of glpc analysis without further purification. Other alkyl acetates were prepared by sulfuric acid catalyzed esterification of the corresponding alcohols with acetic acid in generalla or with acetic anhydride and zinc dust in cases of n-octyl and t-butyl acetates.14 Boiling points of prepared alkyl acetates are indicated as follows: n-propyl, bp 101-102'; isopropyl, bp 87-88'; n-butyl, bp 125-126"; isobutyl, bp 115-117.3'; sec-butyl, bp 110-112.5"; t-butyl, bp 9597.5'; n-amyl, bp 60-61' (31 mm); isoamyl, bp 141-142'; n-hexyl, bp 78.1-80.2' (31 mm); n-octyl, bp 118-123' (44 mm); cyclohexyl, bp 173-175'; benzyl, bp 110' (30 mm). Acetic acid for the kinetic solvent was purified by rectifying 99.5% acetic acid over P z O ~bp , 117.5-118.0'. An acetic acid solution of peracetic acid was prepared by the method described previ0us1y.l~ Authentic samples, iodotoluene, bp 204-207', 4-iodo-l,3-dimethylbenzene,bp 126-129' (28 mm), and iodomesitylene, mp 31', were prepared by the reaction of toluene, m-xylene, or mesitylene with a mixture of iodine and peracetic a~id.~J~ Analyses of Reaction Products.-The products were analyzed by glpc employing a Yanagimoto Model GCG 55OF with a flame ionization detector operated with a 2 m X 3 mm column packed with Apiezon L grease 15% on Celite 545 of 80-100 mesh using nitrogen as a carrier (10-20 ml/min) a t 30-200", hydrogen flow rate 20-30 ml/min, injection temperature 240-330", and detector temperature 240-330'. Identification of products was also done by means of glpc using PEG 20M (3%) 2 m X 3 mm and Silicone SE 30 2 m X 3 mm columns. A 2 m X 3 mm column of Apiezon L grease 15y0 was the most convenient of the three columns. Retention times were longer in the order of alcohols, alkyl acetates, alkyl iodides, and iodo-m-xylene for the samples used in this investigation. Benzene, toluene, or chlorobenzene were used as solvents to extract products from the reaction mixture. Iodotoluene was used as an internal standard for the estimation of iodo-m-xylene by glpc a t 160°, and alkyl iodides or alkyl acetates were used as internal standards for the estimation of other products a t a lower column temperature of 30-120'. All internal standards were added to the extract of the reaction products just before the analyses by glpc. The results are indicated in Table I. Infrared spectra were determined by a Perkin-Elmer Model 333 spectrophotometer. Rate Measurements.-The rate of the reaction of an alkyl iodide, peracetic acid, and m-xylene in acetic acid a t 30.0 =k 0.1 ' was followed generally as described previou~ly.~Aliquots of the reaction mixture were pipetted out into an ice-cooled aqueous potassium iodide solution a t known intervals of time and the amount of peracetic acid was titrated by 0.01 N Na&Oa. In some runs, the concentration of formed iodo-m-xylene was measured by glpc. Second-order rate constants were calculated a t an early stage of the reaction in most cases because a complex reaction may often occur a t a later stage of the reaction. The results are indicated in Figures 1 and 2 and Tables IT and 111.
Registry No.-Peracetic acid, 79-21-0; m-xylene, 108-38-3; iodomethane, 74-88-4; iodoethane, 75-03-6; 1-iodopropane, 107-08-4; 2-iodopropane, 75-30-9; 1iodobutane, 542-69-8; l-iodo-2-methylpropane, 51338-2; 2-iodobutane, 513-48-4; 2-iodo-2-methylpropane, 558-17-8; 1-iodopentane, 628-17-1 ; 1-iodo-3-methylbutane, 541-28-6; 1-iodohexane, 638-45-9; 1-iodooctane 629-27-6; iodocyclohexane, 626-62-0; a-iodotoluene, 620-05-3. Acknowledgment.-The authors wish to thank Daicel Co., Toa-gosei Co., and Tokai Electro-Chemical Co. for their gift of materials, and also Mr. T . Nakamura for his assistance. (13) (14) (15) (16)
A. I. Vogel, J . Chem. Soc., 624 (1948). J. F. Norris and G . W. Rigby, J . Amer. Chem. Soc., 64, 2097 (1932). Y. Ogata and K . Aoki, J . Org. Chem., 82, 4181 (1966). Y . Ogata and K. Nakajima, Tetrahedron, 20, 2751 (1964).
